Pheromones are chemicals released by living organisms that send information to other organisms of the same species via scent. Pheromones are released in response to stress, alarm, danger, sexual fertility, and in other behavioral contexts. Pheromones, by definition and according to evolutionary theory, are species-specific, that is, they are effective in eliciting an innate response only in members of the same species.
Androstenone (also known as 5-α-androst-16-en-3-one) is a steroid found in a number of vertebrate species but is especially pronounced in the male domestic or wild pig. Androstenone acts as a pig sexual pheromone in that the sexually receptive female will seek the boar and express lordosis behavior in the presence of Androstenone or an intact male pig. Androstenone, the odor of an adult dominant male, also reduces aggressive behavior in younger pigs (McGlone, J. J. and J. L. Morrow. 1988. Reduction of pig agonistic behavior by Androstenone. J. Animal Science. 66:880-884). Androstenone is documented as a social pheromone in the pig that changes adult pig behavior and physiology within the same species.
Chemicals that provide interspecies communication are called allelochemicals. Some compounds are known to be a pheromone in one species, but have been observed to have strong behavioral effects in other species. For example, chemicals produced and released by one species that affect the behavior or physiology of another species to the benefit of the originator but not the receiver are known in the art as allomones (See Grasswitz, T. R. and G. R. Jones (2002). “Chemical Ecology”. Encyclopedia of Life Sciences. John Wiley & Sons, Ltd. doi:10.1038/npg.els.0001716). The production of allomones in natural environments has been mainly observed in plant species, which utilize allomones for example to protect plants against insect herbivores.
A kairomone is another known allelochemical. It is emitted by one species and benefits another species, but does not benefit and often harms the emitter. The production of kairomones in natural environments has been mainly observed in insect species. For example, the Ponderosa Pine tree produces a terpene called myrcene when the Western pine beetle damages the tree. The emission of this chemical then lures more beetles to the tree (See Wyatt, T. D. (2003). Pheromones and Animal Behaviour: Communication by Smell and Taste, First Edition (Cambridge, UK: Cambridge University Press).
A synomone is an allelochemical produced and released by one species that benefits both the emitter and receiver. For example, plants emit odors that work to attract bees. The bees are attracted to the plants to feed and then the bees take the pollen to fertilize other plants/flowers.
Accordingly, the allelochemicals known in the art involve the observation of chemicals produced by one species having an effect on another species to the benefit and/or detriment of the emitting or receiving species. What is described is an allelochemical that affects the behavior and/or physiology of another species (i.e., the receiving species) without additionally having a beneficial or harmful effect on the emitting species and having a novel or unrelated behavioral or physiological effect on the receiving species.
For instance, while domestic dogs are known to bark as part of their normal method of communication, dogs may show excessive barking/jumping/mobbing/begging in response to external cues or due to boredom. Mobbing includes repetitive barking and jumping. Certain dogs will bark and jump in an excitable manner when they hear or see people, animals, vehicles, or machines. One theory is that excessive barking is part of the “mobbing” behavior that pack animals have when they attack a prey species (Lord et al., Barking and mobbing, Behav. Processes, 81:358-368, 2009).
Methods used in the art to stop the barking/jumping/begging syndrome in dogs have included shock collars, odor sprays, and loud noises, all of which work by startling or distracting the dog from engaging in the undesirable behavior. Dog appeasing pheromones, including synthetic compositions believed to replicate certain calming pheromones emitted by dogs, have also been used in the art to treat certain behavioral problems in dogs, but to date, have not been successful in alleviating the barking/jumping syndrome exhibited by certain dogs. Moreover, the pheromones used in the art have not been directed for use with animal species other than the species from which the pheromones are emitted.
Reducing and controlling stress experienced by an animal has very practical applications. Using horses as another example, most interactions between a horse and people begin with handling the horse's head. Whether the horse is being handled for basic husbandry such as stall cleaning, grooming, worming and health inspections or enjoying the horse as a companion by leading, riding, driving and other activities, interactions begin with haltering or otherwise gaining control over the horse's head to direct the horse's movements. Most horses accept this handling with no resistance, but some horses react poorly when people try to touch their head or ears, with behaviors associated with stress, nervousness and anxiety. They might flinch, toss their head, hold their head high and away from the handler, or even rear or try to strike the person attempting to touch their head. Usually handlers try to overcome the horse head-shy problem by training the horse using slow and measured movement, in an attempt to keep the horse relaxed and unstressed. While hoping the horse would gradually adjust to and accept the handling of its head, training horses that are very sensitive to touch can take very long and with no success guaranteed.
Additionally, weaning horses also undergo a tremendous amount of stress. Foals are ready to wean typically between four months and six months of age. However, because the mare-foal bond is extremely strong, weaning foals often experience separation anxiety in the first few days and could behave aggressively and get injured. A weaning foal will vocalize, run/trot, hit the fence (attempting to get back to its mother), and eat less immediately after weaning starts. The stress of weaning may also suppress the foals' immune system and makes the foals more vulnerable to conditions such as colds, flu, strangles and pneumonia. To handlers, weaning foals is equally dreadful at least in those early days. Different weaning techniques are used in the horse operations. Generally more gradual methods are less stressful than abrupt separation by suddenly taking the mare completely out of sight and earshot of the foal. However, even the gradual methods may still fail to control or reduce the stress level of the weaning foal as desired.
Accordingly, it would be desirable to provide methods and compositions comprising a compound known to be a pheromone in one species to positively modify animal behavioral problems in a variety of different vertebrate species. In particular, there is a need in the art for use of compositions comprising one or more INTEROMONEs®, such as Androstenone, to calm, sedate, reduce anxiety, or otherwise positively modify the behavior of a variety of vertebrate species, including the barking/jumping/begging syndrome exhibited by some dogs or to calm anxious dogs or cats or other vertebrate species.